This invention relates generally to gas turbine engine bearings and more particularly to mounting arrangements for such bearings.
It is known to support bearings, such as the large rolling-element bearings used in gas turbine engines, using spring centering cages. The spring constant of such cages can be manipulated to provide a desired stiffness and consequently affect the dynamics and vibration modes of the engine. Particularly in large aircraft turbofan engines, it has been demonstrated that engine dynamics will suffer significantly if such cages are not used.
Many gas turbine engines have at least one sump that includes two or more rolling element bearings positioned in close proximity to each other. These sumps have limited axial and radial space available to be used for bearings, spring cages, intermediate gearbox mounting, damper housings, air and oil seals, air pressurization channels, and oil transport between parts of the sump. The axial and radial space needed for an individual spring centering cage for each bearing, which is greater than required for a conventional stiff bearing mounting, is inconsistent with the need to keep the engine as small and light as possible.